title: Preoperative smoking status and postoperative complications: a systematic review and meta-analysis.
abstract: OBJECTIVE
  To systematically review and summarize the evidence of an association between preoperative smoking status and postoperative complications elaborated on complication type.
  
  
  BACKGROUND
  The conclusions of studies examining the association between preoperative smoking and postoperative complications are inconsistent, thus there is a need for a review and meta-analysis to summarize the existing evidence.
  
  
  METHODS
  A systematic review and meta-analysis based on a search in MEDLINE, EMBASE, CINAHL, and PsycINFO. Included were original studies of the association between smoking status and postoperative complications occurring within 30 days of operation. In total, 9354 studies were identified and reviewed for eligibility and data were extracted. Forest plots and summarized relative risks (RR) including 95% confidence intervals (CIs) were estimated for various complication types.
  
  
  RESULTS
  Of the 9354 identified studies, 107 studies were included in the meta-analyses and based on these, 157 data sets were extracted. Preoperative smoking was associated with an increased risk of various postoperative complications including general morbidity (RR=1.52, 95% CI: 1.33-1.74), wound complications (RR=2.15, 95% CI: 1.87-2.49), general infections (RR=1.54, 95% CI: 1.32-1.79), pulmonary complications (RR=1.73, 95% CI: 1.35-2.23), neurological complications (RR=1.38, 95% CI: 1.01-1.88), and admission to intensive care unit (RR=1.60, 95% CI: 1.14-2.25). Preoperative smoking status was not observed to be associated with postoperative mortality, cardiovascular complications, bleedings, anastomotic leakage, or allograft rejection.
  
  
  CONCLUSIONS
  Preoperative smoking was found to be associated with an increased risk of the following postoperative complications: general morbidity, wound complications, general infections, pulmonary complications, neurological complications, and admission to the intensive care unit.
authors.affiliation: *National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark †Department of Medical Gastroenterology, Hvidovre Hospital, Copenhagen University Hospital, Denmark; and ‡Unit of Medical Psychology, Department of Public Health, University of Copenhagen, Denmark.
authors.forename: Marie
authors.initials: M
authors.lastname: Grønkjær
authors.forename: Marie
authors.initials: M
authors.lastname: Eliasen
authors.forename: Lise Skrubbeltrang
authors.initials: LS
authors.lastname: Skov-Ettrup
authors.forename: Janne Schurmann
authors.initials: JS
authors.lastname: Tolstrup
authors.forename: Anne Hjøllund
authors.initials: AH
authors.lastname: Christiansen
authors.forename: Stine Schou
authors.initials: SS
authors.lastname: Mikkelsen
authors.forename: Ulrik
authors.initials: U
authors.lastname: Becker
authors.forename: Trine
authors.initials: T
authors.lastname: Flensborg-Madsen
mesh_terms: D005260:Female; D006801:Humans; D008297:Male; D011183:Postoperative Complications / Q000453:epidemiology* / Q000209:etiology; D057234:Preoperative Period; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*